Devices for removing oil from fluids are generally known in the art, as are devices for removing solid particles suspended within a fluid. Many of these devices include the use of torturous fluid paths to encourage the separation of fluids of differing specific gravities. Other devices within this field employ large settling tanks for the separation of solid material from the fluid.
There are, however, recurring problems with the use of such tanks and systems for the separation of oily contaminants from machine coolant. These problems include the fact that a complicated structure for passing a fluid through a torturous path will necessarily be complicated to clean, and thus will more easily allow bacteria to accumulate within the oil concentrator. Further, the settling out of particulate matter increases the contaminant content within the oil concentrator thus reducing the cleaning efficiency of the mechanism.
The preferred embodiment of the present invention overcomes these difficulties by employing a rather simple torturous path which is easy to clean and provides little area for bacteria to grow, with a cleaning action which encourages particulate matter to float to the surface and thus be removed with the oily contaminant.
The fact that certain materials of differing specific gravities will separate themselves within a chamber is also known within the background of oil separators. The present invention is directed to providing a mechanism which encourages a thorough cleaning of machine coolant by efficiently removing the majority of contaminants from the coolant. This is accomplished by allowing the materials to separate according to the specific gravity of the various materials with the "light" material of lower specific gravity being skimmed from the surface of the "heavy" material of higher specific gravity. The present invention also provides an apparatus which will encourage the rapid separation of materials within a tank.
The removal of oil contaminants from the coolant is necessary as these substances often harbor bacteria which degrade the machine coolant and cause an unpleasant odor. As the coolant is expensive to produce and expensive to dispose of for environmental reasons, there is a need to extend the useful life of the machine coolant by efficiently and economically removing the tramp oil, metal fines, and other contaminants from the coolant.
The use of machine coolant including cutting oil and the like to cool cutting tools in industry is well known. The present invention is part of a complete machine coolant recovery system including a series of settling tanks for removing large particles and solid materials and an ultracentrifuge employed for removing smaller suspended particles and mechanically emulsified oil from the coolant. Following these steps, the fluid mixture entering the oil concentrator will, however, contain a quantity of tramp oil. This oil finds its way into the machine coolant from leaks within the machine being cooled and from environmental surfaces. Additionally, this tramp oil may contain fine particulate matter, such as minute machine shavings or cuttings known as fines. These fines may range in size from 25 to 30 microns for heavy metals and up to approximately 75 microns for aluminum or lighter metals. These fines are typically suspended within oil bubbles contained in the mixed fluid, and thus are not always removed by the ultracentrifuge. However, the oil concentrator is suited for use without a centrifuge.